For service and parts needs, visit your dealer. You will receive genuine GM parts and GM-trained and supported service people.
Genuine GM parts have one of these marks:

Vehicle Care
California Proposition 65 WarningInstallation Procedure
Prepare all mating surfaces as necessary
Align the body lock pillar outer panel reinforcement.
Drill 8 mm (5/16 in) for plug welding along the edges of the body lock
pillar outer panel reinforcement as noted from the original
panel.
Clean and prepare the attaching surfac ...
Exit Lighting
The headlamps, taillamps, parking lamps, back-up lamps, and license plate lamps
come on at night, or in areas with limited lighting, when the key is removed from
the ignition.
The dome lamps also come on when the key is removed from the ignition. The exterior
lights and dome lamps remain on a ...
Exterior Windnoise
Warning: Refer to Assistant Driving Warning in the Preface section.
Exterior windnoise is louder when the vehicle is driven with one or more
windows down. Exterior windnoise occurs when air passes over
the body panels, the seams, or the openings. Use the following items during the
test drive i ...